Record controlled statistical machine



R. WARREN March 14, 1939.

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RECORD CONTROLLED STATISTICAL MACHINE Filed April e, 1932 A 9 sheets-sheet 5 FIGA. l

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ATTORNEY- -March 14, 1939. R. WARRENl 2,150,256

RECORD CONTROLLED STATISTICAL MACH Filed April 6, 1932 9 Sheets-Sheet 4 'ATTORNEY- March 14, 1939. .R WARREN 2,150,256

.RECORD CONTROLLED STATISTICAL MACHINE Filed April 6, 1952 9 Sheets-Sheet 5 0 70 FIGS' 769 69. r' g 72 6e e8 I 656 6e l e, l, 11ml 11H11 w .1 i1@ -w l66 7l@ $3 6'6 l70 y INVENTOR- fw/mww BY TToRNEY- March 14, 1939. R WARRENv ARECORD CONTRCLLED STATISTICAL MACHINE 9 sheets-sheet 6 Filed April 6, 1932 INVENTOR- March 14, 1939. WARREN 2,150,256

RECORD CNTROLLED STATISTICAL MACHINE 9 Sheets-Sheet 7 Fue@ April 1932 l INVENTOR- r/Mm ATTORNEY- March 14, 1939. R, WARREN RECORD CONTROLLED STATISTICAL MACHINE Filed April 6, 1932 INVENTOR- AfA/ffm WW hm# wil .mul

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RECORD CONTROLLED STATISTICAL MCHINE Filed April 6, 1932 9 Sheets-Sheet 9 FIGJG Zar-.Suu I 2 3 MarchY 14, 1939.

Patented Mar. 14, 1939 UNITED STATES PATENT OFFICE i RECORD CON'lXLLED STATISTICAL HINE poration of New York Application April 6, 1932, Serial No. 603,499

This invention relates to a counting apparatus and more particularly to a system for automatically measuring the perfomance of examinees in response to certain types of examinations. The cost of inspecting and scoring a large number of tests has made it necessary to devise a mechanical answer form for examinations that can rapidly be scored by unskilled clerks. These semi-mechanical tests are in general of the following types: (1) True-false; in which a series of statements is made, any of which may be true or not true. The examinee is directed to mark each of the questions as true or false according to his knownledge of the subject and the number of questions that he marks correctly is his score on the test. (2) Another type of test is the matching test. In this type, two series of facts are given and the examinee is directed to match each fact of one of the series with its related fact in the other. For example, in a given series of events and a given series of different dates, there is one correct date for each event, and if the examinee is Well prepared in history, he can assign to each of the events its date. (3) Another type of test is the multiplechoice test, each question of which consists of a statement followed by several possible phrases that could complete the statement. Only one of the phrases is correct in each question and the examinee is required to select the phrase that he believes is correct. The number of questions correctly completed in this way is the examinees score on the multiple-choice test.

The usual method of expediting the scoring of these tests employs a key sheet" which is supplied to the scorer and which is suitably arranged in accordance with the location of the answers specified on the examination paper. The key sheet'y consists oi" a column of numbers in thc same spaced relationship as the answers in the original test form and scoring consists in matching or comparing the column of responses with the column of correct numbers on the key sheet. The scorer counts and records the number of questions that correspond between response and key and this number is the'examinees score.

The foregoing tests fall in the general class of choice-response and their scoring can consequently be handled by purely mechanical means. It is desirable to devise some mechanical means to handle them, since, in spite of the simplification of the operations, the Work of visually checking large number-s of papers is a tedious and time consuming operation and subject to numerous errors.

(Cl. 23S-61.7)

The machine as constructed consists principally of two parts, a sensing mechanism for reading the responses of the examlnee. and a selecting and Arecording mechanism for determining the correctness of the response and tallying it accordingly. 'I'he examination sheet may be arranged with a plurality of rows of delimited areas in which a mark may be made by means of a pencil or similar instrument. The sheet is then passed through the machine so that each column of delimited areas passes beneath an optical sensing device which successively scans the rows of separate areas. A mark in any particular location will cause the optical system to affect a light sensitive or photo-electric cell which is adapted to operate a relay. Suitable amplifying circuits may be provided or not depending upon the type of cell employed. A key sheet, perforated in accordance with the correct answers, is fed through the machine concurrently with the examination paper. Electrical contact devices cooperate with the perforations in the key sheet and with the photo-electric cell controlled relays to establish a circuit to one counting mechanism if the comparison shows that the answer is correct, and to another counter if the comparison shows that the answer is incorrect. After the examination sheet has been completely passed through the machine, the number of right answersand the number of Wrong answers will have been summarized and the result may be noted on the examination paper or elsewhere as indicative of the examinees rating. The counters may then be restored in preparation for receiving entries under control ofthe next examination paper.

It is therefore the main object of the invention to construct an automatic record controlled tallying device provided with means for classifying data on record sheets and recording the same in accordance with the result of the classification. It is obviously advantageous to eliminate the human factor in this iield of activity since such elimination would save the cost of labor, reduce the possibilities of error, and enable speedier as Well as more accurate interpretation of the significance of the comparison between the examination paper and the key sheet.

A more specific object of the invention is to provide a punching machine which may be controlled by the sensing devices to produce a perforated record of the several responses on the examination paper and which would alsoreceive the result of the responses. This record vmay be in the form of the well-known Hollerith tabulating card from which various analyses may be made with the aid of tabulating machines.

A further specific object of the invention is to provide mechanism for separately tallying responses for separate groups of questions, as for instance, in cases where it is desired to separately tally the responses to the odd numbered ques` tions and to the even numbered questions. Educational research workers believe that if a given test is a fair measure of a students ability, the student would make almost the same score if he took the test again. There is no way of proving this directly, however, since the student cannot be given the same test twice under identical conditions of information and attitude but a given test can be divided into two parts and each part regarded as a separate test given at the same time. If the test is a good one, the students score on each oi the two parts should be about the same. This could be done by regarding in a forty question test the questions from i to 20 as one test and from 21 to i0 as another test, but it is considered better practice to make the two half tests overlap so that they are,in effect, given at the same time and for this reason the odd-even separation of the score is considered more desirable.

This arrangement calls for the provision of two pairs of counters of which one pair will count wrong answers and right answers for the even numbered questions and the other pair will similarly count the odd numbered questions.

It is"possib1e thatan examinee might mark more than one choice for a question. This could result from accident or oversight or it might be due to an examinees belief that the machine only counted up the number of right answers.

If he marked more than one, he would have a better chance of indicating the right one among the several choices and the machine might not take account of his duplicity and would credit him with a right answer. It will not do this, but will instead record the double entry as a wrong answer.

It is necessary to provide a wrong counter as well as a "right counter since in some kinds of tests, for example the true-false, it is agreed that omissions of a question will not count against an examinee as much as a definitely wrong answer to the question. In order` to obtain a count of the correct answers, the wrong answers, and the omissions, we must have the number of rights and the number of wrongs, the diii'erence between the total number oi.' responses and the total number of questions on the test giving, of course, the number of omissions.

Various other obiects and advantages of the invention will be obvious from the following particular description of one form il mechanism embodying the invention or from an inspection of the accompanying drawings; and the invention also constitutes certain new and novel features of construction and combination of parts hereinafter set forth and claimed.V

In the drawings:

Fig. 1 is an elevational view of the record sheet feeding and analyzing mechanism.

Fig. 2 is a detail at an enlarged scale of parts shown in Fig. 1.

Fig. 3 is an end view of Fig. 1 taken substantially along the lines 3 3 of Fig. 1, showing the record feeding drum and the `location of the optical sensing devices and the key sheet or comparison record.

Fig. 4 is a sectional view taken substantially along the lines 4 4 of Fig. 3, showing the optical system in sectional detail.

Fig. 5 is a sectional view looking in the direction oi the lines 5 5 in Fig. 4.

Fig. 6 is a sectional view of the comparison sheet analyzing device,'the section being taken substantially along the line 6 8 0f Fig. 3.

Fig. 7 is a detail of the comparison record holding device, the section being taken substantially along the line 7 7 oi' Fig. 6.

Fig. 7a is a further detail of parts shown in Fig. 6.

Fig. 8 is a detail view of one oi the counting devices and the actuating magnet therefor.

Fig. i) is a detail of the counters together with the mechanism for restoring the same.

Fig. 10 is a plan view of the counter assembly.

Fig. 11 is a diagrammatic View showing the arrangement of the analyzing and comparing mechanism and circuits.

Fig. l2 is a wiring diagram of one of the amplifying circuits.

. Fig. 13 is a detail of 'the space key mechanism.

Fig. i4 is a sectional View of the punching mechanism.

Fig. 15 is a wiring diagram of the electric circuits oi the complete device.

Fig. i6 is a detail of a fragment of the "key sheet" or comparison record.

' Fig. i7 is a detail oi' a fragment of an examina tion paper showing the arrangement of the response areas.

Fig. i8 is a fragmentary detail of a record card perforated in accordance with the fragmentary examination paper in Fig. i7.

'Test form The test form or sheet designated i0 in Fig. 17 is provided with a series of horizontal rows of delimited areas' or marking positions designated II. These areas are also arranged in vertical columns, those in the ilrst column being num.- bered I, those in the second column 2, those in the third 3, and so on. Each horizontal row is given a number which corresponds to the number of a particular question which may also, if desired, be printed on the record sheet Ill. The several areas in any horizontal row correspond to the several possible answers relating to that question. The examinee is instructed to make a mark in or fill in the delimited area corresponding to the answer which he considers correct for a particular question. Thus, for instance, the blackened area in the third position of the irst horizontal line of spaces indicates that the third answer was this particular examinees choice for the first question. His choice for the second question was answer #1; his choice for the third question was answer #2; his choice for the fourth, answer #5, etc.

Record feeding and analyzing mechanism The examination or record sheet I0, when ready for correction, is placed upon a table I2 (Figs. 1 and 4) which is provided with suitable lateral guides I3 (see also Fig. 3). The record sheet is placed on the table face upward and its forward edge moved into engagement with pivoted locating ngers I4. A number of clips I5 are pivotally carried by the feeding drum I6 and are mounted on a common operating rod I1 mounted within the drum. With the parts in starting position as shown in Fig. 1 the clips I5 are in their open position, being so held by a resilient toggle connection comprising linkage connected to a member I8 which is pivoted on the drum IB-at I9 and forms a toggle joint with a rod pivoted at 2| on the drum. A spring 22 on rod 20 serves to hold the parts in position. Member I8 is provided with a roller 23 which immediately upon the clockwise movement of drum I6 will strike a pin 24 carried by bracket 25 which is secured to the frame of the machine.

Further movement of drum I6 will rock member I8 in a counterclockwise direction about its pivot through engagement of roller 23 and pin 24, compressing spring 22 and rocking rod 20 from the position of Fig. 1 to that of Fig. 4. The free end of rod 20 is suitably arranged for s liding engagement with the arm of member I8 with which it cooperates. Counterclockwise rocking of member I8 will rock rod I1 in a similar direction through the link 26 and arm 21 so that the clips I5 move into engagement with the record to hold its leading edge firmly against the drum. The fingers I4 are carried by a rod 28 which carries an arm 29 at one extremity thereof. This arm has suitable pin and slot connection with a bell crank 30 pivoted at 3i toa fixed portion of the machine. With the parts in starting position as in Fig. 1. one arm of bell crank 30 rests upon a shoe 32 carried by the drum I6 so that bell crank 30 is held against the action of its spring 33 and fingers I4 assume a vertical position. As drum I6 commences to turn clockwise. bell crank 30 is released by shoe 32 and spring 33 will rock the parts to the position shown in Fig. 4 wherein finger I4 is held out of the path of the record. Rod 28 supports a pair of arms 28a (see also Fig. 3) which carry a roller 29a. This roller rests upon the drum I6 and holds the record sheet I9 thereagainst.

A motor M is provided for driving the drum I6. The connection between the motor and drum comprises belt and pulley 34, worm and worm wheel 35 (see also Fig. 3) and bevel gears 36, one of which is connected to the shaft 31 of drum i5. As the drum rotates the record sheet Iii is drawn in a circular path by clips I5. As the clip mechanism ree-approaches its starting position, a second roller 23a engages another pin 24a carried by bracket 25. This engagement causes member I8 to be rocked in a clockwise direction or specifically, from the relative position of Fig. 4 to the position it occupies in Fig. 1. This, of course, releases the record sheet which is then free to fall into any suitable receptacle located in the base of the machine. As the drum approaches its home position the shoe 32 will engage bell crank 3il, rocking the related parts back to the position of Fig. l.

'Ihe circuit to motor M which will be here'nafter traced in detail is controlled through a pair of contacts 38, the lower blade of which rests upon an arm 39 (Fig. 2) which is provided with a projection 40 adapted to extend into a slot in the periphery of a disk 4I carried by shaft 31. With the drum I6 in restored position, the relationship of disk 4I and arm 39 is as shown in Fig. 1. A bell crank 42 pivotedl at 43 has an extension underlying arm 39 and upon the rocking of bell crank 42 as hereinafter described in a counterclockwise direction arm 39 will be similarly rocked, causing the closure of contacts 38 and disengaging projection 40 from the notch in disk 4I. Closure of the starting contacts ST in series with normally closed contacts 38 will complete the circuit to motor M and drum I6 will commence turning. If bell crank 42 is permitted to return to its initial position, contact 38 will open to break the motor circuit toward the end of the cycle of rotation of drum I8 since at such time the notch in disk 4I will have again come into alinement with projection 40. From this point drum I6 will coast to home position as in Fig. 1 again closing contacts 38. In this manner a single revolution of drum I6 may be obtained. One arm of bell crank 42 is provided with a cam member 44 pivoted at the free end thereof. This cam member has connected thereto a knob 45 (see also Fig. 3) which upon ninety degrees of rotation will rock bell crank 42 counterclockwise and hold it in such position until knob 45 is again turned through ninety degrees. This obviously will keep contact 38 closed to maintain motor M continuously energized and consequently provides for continuous rotation of drum I6 and permits the continuous feeding of record sheets I0. These circuits will be traced in detail in connection with the description of the wiring diagram.

Key sheet or comparisony record A fragment of the key sheet or control record is shown at 46 (Fig. 16) and is arranged with several pairs of vertical columns designated 46-I, 46-2, 46-3, 46-4, and 46-5. Perforations 41 are made in these vertical columns and are arranged in horizontal rows having the same spacing as the horizontal rows of the areas II on the sheet I0 in Fig. 17. In any horizontal row of the sheet 46 there is provided a perforation for each pair of vertical columns i6-I to 46-5 in either of the two columns of the pair. These horizontal rows are perforated to indicate the correct answer for the correspondingly numbered question. A perforation in the left hand column of a pair indicates a correct answer while a perforation in the right hand column indicates an incorrect answer. Since for any question there is but one correct answer, it follows that the remaining four possibilities are incorrect so -that in any horizontal row of perforations 41 there will be one perforation in one of the left hand columns of the several pairs and there will be a perforation in the right hand column of each of the remaining pairs; for instance, in the horizontal row relating to question No. 1 there is a perforation in the right hand column of pairs Mi-I to iS-4 and a perforation in the left hand column of pairs 46-5 indicating that the fifth possible answer is the correct one forI this question No. 1. In question No. 2, the perforation in the left hand column is associated with pair 46-2 indicating that the second possible answer is the correct one for the second question. Similarly, answer No. 3 is indicated as the correct answer for question No. 3.

This key sheet is fastened about drum I6 as shown in Figs. 3 and 6, and secured to the drum by inserting the ends thereof into a longitudinal aperture in the drum. The ends of the sheet are held against the opposite sides of the aperture by spring-pressed members 49 mounted upon a rod which is pivoted to the drum as shown in Fig. '7.

Members 49 are adapted to press against opposite sides of the aperture under the influence of springs 48 and to hold the record sheet 4S thereagainst. Rod 50 is provided with a handle 5I which when rocked in a clockwise direction as viewed in Fig. 6 will, through a pin 52; release the members 49 pressing against one side of the aperture, thus freeing the end of the paper against which they bear. Rocking of the handle Il in the opposite direction will similarly release the oppositely pressing members 49 to free the other end o! the sheet. The "key sheet is thus removable from the drum I0 and it will be understood, oi' course. that a diil'erently perforated "key sheet is used for each set of test forms passed through the device.

With the key sheet 48 in position on the drum, the pairs of columns l-l to 48-5 coineide with strips oi conducting material 53I to 53-5, respectively, and also cooperate with sets o! brushes 54 of which. there is a set for each column of perforations. The brushes 5l are so located that they cooperate with' the row of perforations relating to a particular question at the same time that the row of delimited areas on sheet I0 relating to the same question is beneath the sensing mechanism at the other side of the drum I6.

Record analyzing mechanism Referring to Figs. 4 and 11, the optical analyzing system comprises a plurality oi incandescent lamps 55 mounted in sockets 56. The image of the lamp illament is projected through a lens system generally designated 51 within which is seated a disk 50 provided with an elongated tapered opening 59 (see also Fig. 5). This opening causes the projection of a beam of light corresponding in outline to one oi' the delimited areas on the record sheet. This light is reflected from the sheet through a illter 60 to a photoelectric cell 5| of the gas filled type.

Various types of photo-electric cells may be employed, the type known as a caesium cell be ing considered preferable. This cell is particu larly sensitive to red and infra-red light. For this reason the printing on the test form is done with red ink and since all the light that is reflected from the sheet must pass through the illter which is also red, the cells will respond only to the black marks made in the enclosed areas by the examinee and will not respond to the red printing.

Counting mechanism The counters used in connection with this mechanism arel of the magnetically operated Veeder type and are shown in Figs. 8, 9, and 10. A set of four counters We, Wo, Re and Re are provided, each having an operating magnet 06 which, upon energization, rocks its pivoted armature 61 which, in turn, through links 68 actuates the counter shafts 6! to enter 1 into their respective counters. At the opposite end of each counter a pinion 10 is provided in place of the usual resetting knob common in this type of counting mechanism. A rack 1| meshes with the pinions ot counters We and Re and a similar rack 12 meshes with the pinions of counters W0 and R0; these two racks are tied together by cross bars 12. Rack 12 is provided with teeth on its underside meshing with a toothed sector 14 which is heldin the position shown in Fig. 9 by a spring 15. The sector is provided with a handle 16 which when depressed will move racks 1| and 12 toward the right as viewed in Fig. 9, causing the counterclockwise rotation of the several pinions 10 which results in the restoration of the counters. Each counter has associated therewith a normally closed contact 11 as shown in Fig. 8. Rocking of armature 61 will cause the link B8 secured thereto to open contact 11 through the medium of a block of insulating material 18.

aisance Punchmg mechanism The punching mechanism will now be described. This mechanism is oi' the type shown in the patent to Lee and Phillips No. 1,772,186, issued August 5, 1930, in which the operation oi the punching machine is fully set forth and the present description will therefore be limited to a brief explanation of the punching section su!- ilcient for an understanding of its cooperation with the present machine.

The punching mechanism associated with the device is shown in Fig. 14 and comprises a card carriage rack 18 provided with a card pusher 1l which is adapted to move the cardto the ieit step by step as the carriage is escaped. The usual row of punches 8| is disposed above the card and is normally held in raised position by springs I2. Above each punch 8| is disposed an interposer 03 slidably mounted for horizontal movement. De pression of a key B4 will, through bell crank ill, move its associated interposer t3 to the lei't into position where its upper left hand corner lies under a bar 86. Bar 88 is secured to a bail 81 pivoted at 88 Aand which through link 89, bell crank t0, and link 9| is connected to the free end oi armature 92 of punch magnet 93. Energization of magnet B3 will rock bali 81 in a counterclockwise direction depressing interpsser 33 and the punch 8| over which it lies, to force the punch through the record card 80. With the interposer 83 in retracted position as in Fig. 14, rocking of bail B1 will, of course, not eil'ect either the interposer 83 or its associated punch 8|. Each interposer 83 is provided with a notch 94 against one side of which rests a pivoted plate 95. A hook member 56 cooperates with plate d5 in such manner that the movement of interposer B3 to the left will cause plate 95 to rock in a counterclockf wise direction and draw hook 98 also to the left. The rear end of hook 98 is provided with a lateral extension 91 adapted upon movement of the hook 96 to the left to close a pair oi contacts 98. These contacts are wired in series with magnet 93 and upon closure will energize the magnet in a manner to be more fully described in connection with the wiring diagram.

Magnets 39 are provided which upon energizetion move their associated armatures |00 downwardly. The free ends of these armatures are connected to keys 84 so that energization of a magnet 99 will move its corresponding key downwardly to cause the operation of the related punch 8|. Downward movement of any interposer B3 by bar 86 will rock a bail 10| in a counterclockwise direction also rocking a rod |02.

Rod |02 (see also Fig. 13) controls the step by step escapement mechanism which comprises the usual-holding paw] I 03 and the stepping pawl |01. The action is such that rocking oi rod |02 in a counterclockwise direction will lower pawl |04 into engagement with a tooth of carriage rack 18 and will raise pawl |03 out of engagement therewith. Restoration .of shaft |02 will again raise pawl |04 and permit pawl |03 to move into engagement with the next tooth of the rack thus eiecting a spacing operation.

In Fig. 13 an interposer bar 83a is shown. This bar has its forward end normally underlying bar 8B so that rocking of bar 86 at any time will rock bail |0| to effect spacing regardless of whether punching is also effected or not. Bar 83a is as sociated with space key 84a and had no punch related thereto.

Two pairs of contacts |51 and I 1| are soarranged (Fig. 14) that downward movement of link 89 under the influence of magnet 93 will open both the contacts at the end of the downward movement'of link 89.

Wiring diagram The wiring diagram of the entire mechanism is shown in Fig. 15. A source of current supply is indicated at S and a start key at ST. When the machine is connected to the source S,a circuit is immediately completed through the lamps 55 from the left side of the source, through a wire |05, wire |06, lamps 55 and resistances |01, wires |08 and |30, back to right side of source. this circuit including resistances |01, the lamps will burn at a low brilliance and warm up sufficiently so that they will immediately come to full brightness as soon as the apparatus begins to function.

With the record sheet I in starting position, depression of start key ST will complete a circuit from source S, through wire |30, contact ST, relayv coil |09, motor M, normally closed contact 38, Wire |05, to source S. Relay |09 will close its points |09b to include resistances |01a in the lamp circuit to increase the brilliance of the light. Points |09a upon closure, will set up a holding circuit for motor M from source S, to wire |05, contact 38, motor M, relay coil |09, points |09a, wires |08 and |30 back to source S. The motor will thus remain energized until contact 38 breaks toward the end of the cycle. It will be recalled that contact 38 may be latched in closed position in which case motor M will remain in operation until the contact 38 is released.

Each photo-electric cell 6| (see also Fig. 12) is connected by means of a conductor I6 to a battery ||1 and through a conductor |8 to the grid ||9 of a three-element tube |20. Shields |2| are provided on the cell leads to prevent disturbances due to stray fields.

Tube |20 contains a filament |22 kept hot by wires |23 connected to a source of current and surrounded by the .grid ||0 through which must pass all of the electrons emitted from the hot larnent on their way to the plate |24. The plate is kept at a higher potential than the filament in order to attract these electrons and the potential of the plate varies with the amount of current flowing in the plate circuit. This plate current can be controlled by varying the potential onthe grid through which the current electrons must The grid is normally kept at a potential slightly lower than the negative end of the filament, and is adjusted by means of the grid potentiometer i725.

The second tube |26 of the amplifier is a power tube designed to pass a fairly large plate current and has a comparatively low internal resistance. Its purpose is to respond to a signal voltage by releasing a large current through a comparatively low resistance as in relay coil |21.

If the photo-electric cell 6| is connected directly to the grid ||9 of the first amplifier tube |20, the potential of the grid will be at every instant the same as the potential of the plate of the photo cell and the plate of the first tube will follow in greatly amplified ratio all of the small changes in the potential of the grid and photo cell. These small changes may be due to variations in the power that lights the filaments of the lamp used as a light source, or to shadows falling on the cellor toa slight difference in the color of two different sheets being analyzed. The first tube |20 amplies so much that it does not require much change in light flux to produce a very large change in the output voltage of the with' first tube. In fact, Variations in light due to the changes in the lighting power supply that are too small to be observed by the eye will result in a change in the plate output voltage large enough to throw the circuit out of adjustment. `For this reason it is necessary to arrange the coupling between the photo cell and the rst tube in such a manner that a change in light flux will only have a temporary eiect on the system, and that will permit the grid of the tube to go back to its normal operating position without regard to the total light flux that happens to be acting on the cell at that moment. 'I'his is done by making the tube respond to the changes in voltage rather than to the total voltage itself. A condenser |28 is introduced between the high voltage end of the vphoto cell output resistance ||4 and the grid H8.

The condenser |28 will pass current only during the time that the E. M. F. is changing. After the E. M. F. has changed and has reached a new value, the condenser no longer passes any current, and the potential of the grid returns to its normal position. The arrangement then will respond to changes in light flux but will automatically readjust itself after each change, no matter what the value of the total light reflux is.

While the light is focused on the blank record and reflected from the cell 6|, the resistance of the cell is substantially constant, the charge on condenser |28 is likewise substantially constant, and the grid of the vacuum tube is held at a small negative potential by the battery. The value of this negative grid potential is such that it permits the flow of a limited but constant amount of space current. Relay |21 is in the plate circuit of tube |26 Whose grid is controlled by the plate current from plate |24 through condenser |5 and will therefore be in its open position. When a pencil mark cuts oli the light momentarily, the resistance of cell 6| becomes greater and the charge on the condenser |28 is changed, resulting in a flow of current through the grid resistance, thereby increasing the negative potential of the grid suicient to reduce the flow of space current through the tube |20. This changes the charge on condenser ||5 and consequently on the grid of tube |26 which causes the energization of relay |21. Relay |21 thereupon closes its points |21a.

Closure of points |21a (Fig. 15) will establish a circuit from source S, wire |30, points |21a, wire |3|, relay coil |32 to the two central brushes 54 of the set of brushes cooperating with the pair o columns on the comparison record 46 associated with the column of the answer sheet I0 controlling coil |21 (see also Fig. 11). From here the circuit will branch to the left or right to one of the outer brushes 54 of a set through metallic strip 53| to 53-5 depending upon whether there is a perforation 41 in the left or right column of pairs 46| to 46-5. It will be understood, of course, that brushes 54 sense these perforations 41 concurrently with the analysis by the photo-electric apparatus of the corresponding response rows of marked areas Specifically, if there is a mark in the fifth column of sheet I0 and there is a perforation in the right column 46-5 (as viewed in Fig. 11) of the same question the circuit will continue from the right one of central brushes 54 of column 5 through perforation 41, contact strip 53--5, next adjacent brush 54 to the right wire |33, choke coil |45, relay points |34a, wire |35, relay coil |36, wire |31, wire |05, back to source S.

Energization of coil |36 will cause closure of its points |36a to enact a circuit as follows: from source S, wire |30, wire |38, lower relay points |39a, wire |40, points |35a, magnet 56 of the upper "right" counter Re andwire |31 to source S. A parallel circuit runs from points |36a to contacts 11,y coil |35, wires |31 and |05, to source S, thus setting up a holding circuit for relay coil |36. Energizatlon of magnet 6B will cause one" to be added to its associated counter R...

With the perforation 41 in the left column of pairs 46--5 (as viewed in Fig. 11) the circuit from the left central brush 54 will `continue through such perforation to the strip 53,-5 to the next adjacent brush 54 on the left and thence through wire |42 to relay points |3412, wire |43, relay coil |38, wn'es |44 and |05 to source S. consequent closure of upper points |39a provides a circuit from source S, wire |30, wire |33, upper points |33a, contacts 11, coil |39, wire |44, wire |05, back to source S, and a parallel circuit from upper points |33a, magnet 55 of the upper left counter We, wires |44 and |05 to source S.

It will be noted that the two upper counters W. and R. are controllable from' any set ol' brushes 54, counter Re being actuated ii.' there is a perforation in any right hand column 46| to 45-5 and counter WQ being actuated if there is a perforation in any left hand column. The circuit to counter Re must pass through the lower relay points 39a which are controlled by the circuits oi' counter Wa so that as long as relay I 33 is deenergized, the circuit for counter Re may be established. When more than one relay |21 is energized, due to the marking of more than one enclosed area in any row o1' the record sheet, the tendency will then be to energize coils |35 and |33 simultaneously but a choke coil |45 in wire |33 leading to coil |35 will cause the circuit therethrough to lag, permitting the more rapid circuit to relay |33 to effect opening of lower relay points |33a and prevent completion or the other circuit. In this manner, a double response to any question on the examination paper will be recorded as a "wrong answer even though one of the responses may be a correct one. Energization of magnet 55 will cause opening oi associated contacts 11 to drop the holding circuits of the relays |36 and |33. Resistances 200 are provided, one oi' which is in series with relay |35 in the pickup circuit of this relay. The other is included in the holding circuit of magnet |35 traced through contacts 11. These resistances 200 are ot such value that the initial circuit through wire |35 is effective only through the relay |36.

Below counters We and Re are counters Wo and R@ upon which may be tallied the odd numbered responses. The circuits to-these counters are similar to those for counters We and Re; extending-from wires |33 and |42, through the left hand pointsl |34a and |34b of relay |34 and wires |45 and |41 which correspond to Wires |35 and |43 respectively. From here the circuits are identical with those already described and will therefore not be repeated.- Similar parts are given similar reference characters.

Relay |34 is controlled by a pair of brushes 54a which traverse a column of the comparison record 46 designated |48 in Fig. 16. In this co1- umn perforations |41a are made in the horlzontal row positions representing the odd numbered responses. Slightly before the response to each odd numbered question is analyzed and identied as "right" or "wrong" by the comparison record, a circuit is completed from source S.

eration. 'I'he card will thus Wire |30, brushes 54a, perforation 41a, metal strip |49 (see Fig. 3) switch |50 (now closed), relay |34, wires |5| and |05 to source S. Energization of relay |34 shifts its armature to open points 34a, |34b on the right and close its points to the left thereby shifting entry from counters We, Rs to counters W0, R0. This separate tallying of odd and even responses may be incapacitated by opening switch |50 in which case only the upper counters are used. It is quite obvious that perforations |41a may be so located that entries may be made into counters W0, R0 from any other positions of the record |0, than those shown in connection with the particular application under consideration.

As mentioned above, a relay |32 is included in each wire |3| leading to central brushes 54.

The points |32a of each relay are connected to a common wire |52 which connects to source S through wire |30. Closure of a point |32a will continue the circuit through a wire |53, relay coil |54, Wire |55 to source S, energizing the relay |54 and causing closure of its points |54a. This sets up a holding circuit running from source S, wire |56, contact |51 (normally closed) wire |55, relay points |54a, relay |54, wire |55 back to source S. This circuit will remain established until opening of contacts |51 by the action of punch magnet 93,

A further circuit may now be traced from source S. wire |50, contact |51, wire |58, points |5411, wire |50 to the appropriate interposer magnet 39, normally closed contacts |50, |6|, wire |55, back to source S. Energization of magnet 38 will thereupon move its interposer forward into cooperation with its punch.

During record sheet analysis, while motor M is in operation, a circuit may be traced as follows: from source S, wire |05, contacts 38, motor M, wire |52, relay |63, wire |54 to source S. This circuit is completed as long as motor -M remains energized thus keeping points |63a in the position shown on the circuit diagram. This opens the circuit between punch magnet 93 and contact 98, preventing the operation of the punch under key control while motor M is operating.

Key sheet 46 (Fig. 16) has a column of perforations |65, one for each horizontal row of perforations 41 and located so as to cooperate with brushes |65 (Figs. 3, 11 and 15) shortly after brushes 54 sense perforations 41. At this time a circuit is established from source S to wire |30, wire |52, one of the brushes |65, hole |55, conductor strip |51, other brush |55, wire |53, relay |53, wire |56 to sourceS. Relay |53 closes its points |59a'and current will S, wire |55, wire |10, points 69a, contact |1i, relay |59, to source S through wire |55. 'Ihis is the holding circuit for the relay which is broken upon opening of contacts |1| by the action of punch magnet 93. The punch magnet circuit is now completed from source S, wires |55, |10, points I 59a, lower points |53a, punch magnet 03, Wire |55, back to source S. Punching thereupon takes place in the positions in which interposer magnets 99 have been energized.

Where no response is made i'or a particular question and consequently no counter actuation takes place; punch magnet 93 will nevertheless be energized to cause spacing without punch opshow by a blank column that the question to which it corresponds has not been answered.

Recapitulaton In order that the complete operation of the iiow from source a selected answer.

machine may be better understood, a rsum of:k

the entire sequence of operations as performed"k by the machine will now be given in connection with the application of the device to the scoring of examination papers and the reproduction of the 'examinee's responses in perforated card form.

After the examination paper has been placed on the table I2 and its leading edge moved into engagement with the locating iingers I4, start key ST is depressed which will complete the motor circuit and drum I6 will commenceto rotate. As the iirst r'ow of response -areas il of the examination sheet arrives beneath the lenses B1 and the first row of perforations 41 arrives at the sensing positions, circuits will be completed under control of the photo-electric cells 6|, in accordance with the manner in which the examinee has recorded his response to the first question. If he has made a mark in the area related to the correct answer, the circuits will be completed in the manner outlined in detail above to add 1 in the counter which accumulates the number of correct answers. At the same time a branch circuit will be completed to the punch magnet corresponding to the answer selected by the examinee. This will cause the perforation of the record card B of Fig. 18 in the first column thereof and in the index point position corresponding to the selected answer.

If the examinees response is noted in one of the areas other than that corresponding to the correct answer, the circuits will be controlled to enter a l in the counter which accumulates the number of wrong answers. The circuits will also eilect the perforation of the record card in the index point position corresponding to the It will thus be noted that a mark made in any delimited area Il of a row of such areas may either cause the entry ofl into the "wrong counter or into the right" counter in accordance with the configuration olf the comparison sheet 46. punch. however, in either case, will be such as to perforate the corresponding position in the column of the record card regardless of the signicance of the mark itself.

Where there is more than one perforation in a horizontal row, a single entry of 1 is made in the "wrong counter. The punching device, however, will take account of each separate mark and perforate the corresponding column of the record card in each position for which a mark has been made. Where a horizontal row is left blank, the counters will, of course, remain inoperative and the punching mechanism will be operated to space one step. The speed of rotation of the drum I6 is timed so that as each row of areas ll passes the optical` device the step-by-step escapement mechanism of the punch will be operated so that as, let us say, the twentieth row of response areas is being analyzed by the optical system, the twentieth column of the record card is in position to receive perforations therein. After the examination sheet I0 has been completely analyzed, the score as tallied by the counters may be noted thereon or, if desired, this result may be manually perforated on the record card 80 by means of the keys 84 of the punching mechanism. The counters are then reset and this card 80 may be replaced by a new card and a new examination paper placed in position. l

If it is desired to separately tally the odd and even questions, the switch |50 of Fig. l5 is closed and the right and wrong answers of the odd questions will be tallied separately from the The control of the' right and wrong answers of the even questions. The operation of the punching mechanism will-however, take place regardless of the distribution of the results.

' While there has been shown and described and pointed out the fundamental novel features of the invention as applied to a single modification, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is: l

1. In a machine of the class described, means for analyzing an examination response sheet for marks representative by their location on the sheet of right and wrong answers, counting devices controlled by said analyzing means and means including a second sheet and sensing means therefor for determining. in accordance with their location the significance of the marks analyzed and for causing the operation of the counting devices in accordance with said determined signiiicance.

2. In a machine of the class described, means for analyzing predetermined areas of a record for marks therein, each mark having in accordance with the location of the area in which it is made, one oi' a number of signicances, means including a second record and sensing means therefor for determining the significance of each mark analyzed, and means including a plurality of counters controlled by said analyzing and determining means for separately counting the marks having the same signicance. 3. In a machine of the class described, lightsensitive means for analyzing a record sheet for indicia marked thereon, aplurality of counters and means including a pattern sheet and analyzing means therefor, cooperating with said first named analyzing means for selectively associating one of said counters with said first named analyzing means for control thereby.

4. In a machine of the class described, a record sheet having perforations, light-sensitive means for analyzing a record sheet with indicia marked thereon, a counter controlled by said analyzing means to count said indicia, means for analyzing said first named'record sheet and'means controlled by said last named analyzing means for preventing the operation of said counter under con-trol of said first named analyzing means.

5. In a machine of the class described, means for optically analyzing a record having indicia marked thereon and arranged in columns, a counter controlled by said analyzing means for counting marks insaid columns, means cooperat- 'ing with said analyzing means for rendering said counter ineffective to count marks in certain positions in the columns of the record and means fo pre-selecting said certain positions. f

6. In a machine for tallying responses to an examination, means for analyzing a response sheet having variously located positions in which markings are adapted to be made, a comparison sheet having correspondingly located positions in which perforations are made indicative of correct and incorrect answers, means for analyzing said comparison sheet concurrently with the anaiysls of said response sheet, a counter for counting correct answers and means jointly controlled by both of said analyzing means to control said counter to count they markings on the response sheet corresponding to Apositions on the compari- SOn sheet punched to indicate correct answers only.

7. In combination, means for analyzing a record sheet having indicia marked thereon, said means including a light source, light-sensitive means actuated by the light source, a plurality of circuits completed by said light-sensitive means; a plurality of counters, one for each circuit and record controlled means for selecting one of said circuits to control the related counter.

8. In a machine of the class described, means for analyzing a response sheet having a plurality of marking positions in one of which a mark may be made to designate a selected answer, means for concurrently analyzing a comparison sheet having a pair of marking positions for each marking position of the response sheet, one of said pairs of marking positions containing a mark indicating a correct answer and each of the other pairs being marked to indicate incorrect answers, a counter for correct answers, a counter for lncorrect answers, operating means for each counter, means jointly controlled by said analyzing means, when the pair of marking positions on the comparison sheet corresponding to the position marked on the response sheet are marked to indicate a correct answer, for causing the operating means of the correct answer counter to operate said counter, and means jointly controlled by said analyzing means, when the pair of marking positions on the comparison sheet corresponding to the position marked on the response sheet are marked to indicate an incorrect answer, for causing the operating means of the incorrect answer counter to operate said counter.

9. In a machine of the classl described, means ior analyzing a response sheet having a plurality of marking positions in one oi. which a niark may be made to designate a selected answer, means for analyzing a comparison sheet having a pair of marking positions'for each marking position of the response sheet, one of said pairs oi marking positions containing a mark indicating a correct answer and each of the other pairs being masked to indicate incorrect answers, a counter :for correctfanswers, a counter for incorrect answers, operating means for each counter, means jointly controlled by said analyzing means, when the pair of marking positionsl on the comparison sheet corresponding to the position marked on the .re-- sponse sheet are marked to indicate a. correct answer, for causing the operating means of the correct answer counter to operate said counter, and means jointly controlled by said analyzing means, when the pair of marking positions on the comparison sheet corresponding to the posttion marked on the response sheet are marked to indicate an incorrect answer, for causing the operating means of the incorrect answer counter to operate said counter.

l0. In a machine of the class descrihed, means for analyzing a response sheet having a plurality of marking positions in one of which a mark may be made to designate a selected answer, means for analyzing a comparison sheet having a pair of marking positions for each marking position oi.' the response sheet, one of said pairs of marking positions containing a mar i indicating a correct answer and each of the other pairs being marked to indicate incorrect answers, a counter for correct answers, a counter for incorrect answers, a circuit, including a magnet, com

pleted by said analyzing means jointly when the pair of marking positions on the comparison sheet corresponding to the position marked on the re sponse sheet are marked to indicate a correct answer, means controlled by said magnet for causing operation oi' the counter for correct answers, a second circuit, `including a second magnet, completed by said analyzing means jointly when the pair of marking positions on the comparison sheet corresponding to the position marked on the response sheet are marked to indicate an incorrect answer, and means controlled by said second magnet for causing operation of the counter for incorrect answers.

11. In a machine of the class described, means for concurrently analyzing a plurality of marking positions on a response sheet, in one of which a mark may be made to designate a selected answer, means for analyzing a comparison sheet having a column of marking positions for each marking position of the response sheet, one ci said columns having a mark positioned to designate a correct answer and the others each having a differently positioned mark to designate incorlq rect answers, a counter for correct anso/eran counter for incorrect answers, an operating Inagnet for each counter, normally open operating circuit connections for each magnet, means controlled by said analyzing means jointly when the mark on the response sheet is made in the position corresponding to the column on the comparison sheet marked to indicate the correct anu swer, for completing the circuit connections to the magnet associated with the correct answer counter, and ineens controlled hy said means jointly, when a niark on the response sheet is made in any other position ior completing the circuit connections to the magnet associated with the incorrect answer counter.

l2. ln a machine of the class described, mea for concurrently analyzing a plurality ci mart positions on a response sheet, in one of which c niark may he marie to designate a selected answer, a plurality ci main circuit connections, one icc each marking position, a pair oi parallel lortu connections extending iroin each main cornice tion, a common return connection ior one ot each pair ol loranch connections, a second common return connection for the other oi each. pair oi branch connections, a correct answer counter, an operating control magnet therefor included one return connection, an incorrect answer counter, an operating control magnet therefor included in, the other return connection, means including correct answer selecting means for elecM trically connecting a branch of one ci said main connections to the return connections related to the correct answer counter, means including incorrect answer selecting ineens for connecting the other branch ol? each of the other pairs oi branches to the return connection related. to the incorrect answer counter, a source ci current connected on one side to said return connections, and means controlled by said analyzing means for connecting the main circuit connection correl spending to the position containing a mark to said source of current whereby a circuit will he completed through one of the branches of said. main connection and its return connection dem pending upon which is connected by the afore-n said correct and incorrect answer selecting means.

13. The invention set forth in claim lll in which the correct and incorrect answer selecting means comprise a record sheet having perforations through which the electrical connections are made.

lll. In a machine of the class described, means for sensing a succession of rows of marking posi tions of a response sheet, one by one, means for concurrently sensing a corresponding succession .of rows of marking positions of a comparison lill currently sensed, a second pair of counters and means controlled by another part of said second sensing means upon sensing a special mark in the pair of rows concurrently sensed for preventing control of said rst pair of counters and causing the second pair of counters to be controlled by the rows being sensed.

15. In a machine of the class described, means for sensing, in succession, a plurality of rows of marking positions on a response sheet, in each row of which a mark may be made to designate a selected response to a question, two pairs of counters, one counter of each pair for counting correct responses and the other counter of each pair for counting incorrect" responses, settable devices adjusted in accordance with the correct and incorrect answers for each row of the response sheet, adjusting means therefor, means controlled by said sensing means and said settable devices for causing operation of the counters in accordance with the correctness or incorrectness of the responses, selectively adjustable means and control means therefor for causing one pair of counters to be controlled to count the responses in the odd numbered rows of the sheet and the other pair to be controlled to count the responses in the even numbered rows of the sheet whereby a separate count is obtained of the nurnber of correct and incorrect responses for the odd and even numbered questions.

16. In a machine of the class described, means for sensing, in succession, a plurality of rows of marking positions on a response sheet, in each row of which a mark may be made to designate a selected response to a question, two pairsof counters, one counter of each -pair for countingcorrect responses, and the other counter of each pair for counting incorrect responses, settable devices adjusted in accordance with the correct and incorrect answers for each row of the response sheet, adjusting means therefor, means controlled by said sensing means and said settable devices for causing operation of the counters in accordance with the correctness or incorrectness of the responses, selectively adjustable means and control means therefor for causing one pair `oi' counters to be controlled to count the responses in certain selected rows of the sheet and the other pair to be controlled to count the responses in the remaining rows of the sheet.

1'7. In a machine of the class described, means for sensing in succession a plurality of rows of marking positions on a response sheet, in each row of which a mark may be made to designate J a selected response to a question, two counters,

for causing operation of said counters when the selected response is the correct answer, selectively adjustable means and control means therefor for causing one counter to be controlled to count the correct responses in the odd numbered rows of the sheet and the other counter to count the correct responses in the even numbered rows of the sheet.

18. In a machine of the class described, means for sensing, in succession, a plurality of rows of marking positions on a response sheet, in each row of which a mark may be made to designate a selected response to a question, two counters,

settable devices adjusted in accordance with the correct answers for each row of the response sheet, adjusting means therefor, means controlled by said sensing means and said settable devices for causing operation of said counters when the selected response is the correct answer, selectively adjustable means and control means therefor for causing one counter to be controlled to count the correct responses in certain selected rows ofy the sheet and the other counter to count the correct responses in the remaining rows of the sheet.

19. The invention set forth in claim 18 in which the selectively adjustable means is an electrical switching device and the control means therefor is a record controlled circuit closer arranged to operate the switching device during the sensing of the said certain selected rows on the response sheet.

20. In a machine of the class described, means for analyzing a response sheet having a row of marking positions in one of which a mark may be made to designate a selected response, a counting device, a plurality of switching devices equal in number to the plurality of said marking positions, means for causing operation of one of said devices to represent a correct answer, a circuit inoludi-ng a magnet, completed by said analyzing means and the operated switching device when the position marked on the sheet corresponds to the switching device operated and means controlled by said magnet for operating said counting device.

21. In a machine of the class described, means for analyzing 4a response sheet having a row of marking positions in one of which a mark may be made to. designate a selected response, a plurality of switching devices, one for each marking position, means for causing operation of one of said devices to represent a correct answer and a circuit including electrically responsive means completed by said analyzing means and the operated switching device when the position marked on the sheet corresponds to the switching device operated.

22. In a machine of the class described, means for analyzing a response sheet having a row of marking positions in one of which a mark may be made to designate a selected response, a plurality of switching devices, one for each marking position, means for causing adjustment of one of said devices to represent a correct answer and the other devices to represent an incorrect answer, a circuit including electrically responsive means completed by said analyzing means and the device adjusted for a correct answer when the position marked on the sheet corresponds to the dev'ice so adjusted, and a second circuit including a second electrically responsive means completed by said analyzing means and any of the other devices adjusted for an incorrect answer when the position marked on the sheet corresponds to one of said other devices.

23. The invention set forth in claim 22 in which a counter is provided for each circuit, each controlled by the electrically responsive means of its related circuit and means operative when both circuits are concurrently completed in response to a mark in a correct answer position and a second mark in an incorrect answer position for preventing the control of the counter related to the circuit completed in response to the correct answer mark.

24. In a machine of the class described, means foranalyzingaresponsesheethavingarow of delimited areas in one or more of which a mark may bemade, means for analyzing a comparison sheet having a correct answer" position for each area and an incorrect answer" position i'or each area, one of said "correct answer positions being marked and all but the corresponding incorrect answer" position also marked, a correct answer counter, an "incorrect answer counter, means jointly controlled by both said analyzing means when a single area is marked on the response sheet and corresponds to the correct position marked on the comparison sheet for controlling the operation o! the correct answer counter, means jointly controlled by both said analyzing means when a single area is marked on the response sheet and corresponds to one of the "inem-rect positions marked on the comparison sheet i'or controlling the operation of the inn correct answer counter and further means controlled by said last named means when the response sheet contains a mark in both an area corresponding to a correct answer and an incorrect answer for preventing the operation of the correct answer counter.

25. A test scoring machine for examination sheets having designations selectively placed. thereon and according to the position placed rep-u resenting answers to questions, comprising a base; feeding means for moving an examination sheet relatively to the base past a. given point; sheet scanning means carried .by the base, ire-- spending to the designations on said sheets; an accumulator; and means `for operating said accumulator from the responses of the sheet manm ning means to correct answer designations, to total the score of answers on the sheet.

26. A test scoring machine for examination sheets having designations selectively placed thereon and according to the position placed representing correct and incorrect answers to quesJ tions, comprising a correct-answer accumulator; means for operating said accumulator according to the correct-answer designations on said sheets, including sheet scanning means responding to said designations; means for feeding sheets relatively to the scanning means; and means for preventing operation of said accumulator when designations representing both a correct answer and an incorrect answer to any one question are scanned by the scanning means.

27. A test scoring machine for examination sheets having designations selectively placed thereon and according to the position placed representing correct and incorrect answers to questions, comprising a correct-answer accumulator: an incorrect-answer accumulator; means for operating said accumnlators selectively according to the correct-answer and incorrectanswer designations on the sheets, including sheet scanning means responding to said designations; means for feeding the sheets relatively to the scanning means; and means for preventing operation oi.' the correct-answer accumulator when designations, representing both an incorrect answer and a correct answer to any one question, are scanned by the scanning means.

28. A test scoring machine for examination sheets having designations selectively placed thereon and aording to the position placed representing corrt and incorrect answers to qutions, comprising a score-totalizing device; means for operating said device selectively according to the correct-answer and incorrectanswer designations on the sheets, including sheet scanning means responding to said designations; means for feeding the sheets relatively to the scanning means; and means for prevent ing correct-answer operation of the. device when en incorrect-answer designation ic scanned by the scanning means.

29. In a test scoring machine through which examination sheets are passed having designations selectively placed thereon and according 'to the position placed representing answers to duestiom, a cylindrical member adapted to turn with advancement of the sheets; a master pattern carried by said member and arranged to corrpond to the designations of a correctly answered examination sheet; and means on said member for engaging an examination sheet to position succesnve portions of the latter prop orly relatively to said pattern as the member turns and the sheet advances through the inachine.

30. The invention as defined in. claim 29, in which the pattern comprises a. removable sheet secured to tlie cylindrical member in predetermined relation to the means for engaging 'the examination RICHARD WARREN. 

